Juvenile mallard (Anas platyrhynchos) drakes were fed diets containing 0, 50, 150, or 450 ppm cadmium for 42±1 days in order to assess the impacts of cadmium ingestion on energy metabolism and tissue metal concentrations in this species. Most significant (p<0.05) effects on energy metabolism were observed only in the 450 ppm group which displayed reduced body and liver weights, increased kidney weights, reduced liver aldolase activity, increased plasma concentrations of uric acid, decreased plasma triiodothyronine concentrations, and elevated adrenal weights and adrenal corticosterone concentrations. Ducks in the 150 ppm group displayed increased adrenal and kidney weights and elevated plasma nonesterified fatty acid concentrations. Among all treatments, increased cadmium and zinc concentrations in both livers and kidneys were dose-related; a similar trend was observed for copper concentrations in kidneys but not livers. Cadmium interference with carbohydrate metabolism in similar studies with mammals was more severe than that observed in mallards in the present study.